The use of portable electronic instruments is increasing as electronic equipment gets smaller and lighter due to developments in high-tech electronic industries. Studies on rechargeable lithium batteries are actively being pursued in accordance with the increasing need for a battery having a high energy density for use as a power source in these portable electronic instruments.
Lithium cobalt nickel oxide is one of the cathode materials for rechargeable lithium batteries. However, the procedure of the conventional preparation method for lithium cobalt nickel oxide is very complex. Conventionally, the nickel salt and cobalt salt are firstly reacted with an alkaline solution, such as potassium hydroxide or sodium hydroxide, to form a co-precipitate of nickel hydroxide and cobalt hydroxide. The co-precipitate is then washed repeatedly with water to remove the residual potassium ions and sodium ions. Afterwards, the washed co-precipitate of nickel and cobalt hydroxide is thoroughly mixed with the lithium hydroxide and then followed by a solid reaction method for converting into layer-structured lithium nickel cobalt oxide. In the conventional solid reaction method, a long period of mixing and a long period of high temperature heat treatment are necessary to obtain the desired powders. Therefore, the conventional process is time and energy-consuming. Furthermore, the purity and the uniformity of the powders resulted from the solid reaction method are usually low due to the contamination occurred in mixing and grinding and the incomplete mixing.